Adjustable antenna rod and support assembly



p 13, 1966 J- A. KOSTER 3,273,097

ADJUSTABLE ANTENNA ROD AND SUPPORT ASSEMBLY Filed May 21, 1964 FIG.3

INVENTORv JOHANNES A. KOSTER United States Patent 3,273,097 ADJUSTABLE ANTENNA ROD AND SUPPORT ASSEMBLY Johannes A. Koster, Scarborough, Ontario, Canada, as-

signor to North American Philips Company, Inc., New

York, N .Y., a corporation of Delaware Filed May 21, 1964, Ser. No. 369,238 Claims priority, application Canada, July 3, 1963,

6 Claims. (01. 336-65) This invention relates to an adjustable inductance as sembly comprising a ferrite rod core movable in a wound coil to provide tuning, and a support therefor, the support acting in addition as a locking means to secure the core in the desired position in the coil.

Known-assemblies, widely employed as the antenna element of broadcast radio receivers, normally incorporate an adjustable core which is substantially longer than the wound coil. The core is secured on a radio chassis by rubber gromments held in spaced support members. Adjustment of the antenna inductance is accomplished by moving the coil, mounted on a coil form surrounding the core, axially of the core to provide the proper inductance required for tuning the broadcast band with the variable capacitor tuning means of the radio receiver. The coil form is then secured to the core in position and this is generally accomplished by means of wax. The adjustment of the inductance can .be easily disrupted before or while applying the wax.

It is an object of this invention to provide an inductance adjustment locking means which is not subject to disturbance by mechanical shock while being readily releasable.

It is a further object of this invention to provide an inductance adjustment locking mean which acts additionally as an inductance mounting means.

It is still a further object of this invention to provide a mounting and locking means which is simple, reliable and economical.

The invention will now be described with reference to the figures of the drawing in which a preferred embodiment is illustrated,

FIGURE 1 shows a vertical view of a preferred form of the adjustable inductance and mounting means assembly.

FIGURE 2 shows .a plan view of the assembly of FIG- URE 1, and

FIGURE 3 shows the mounting means prior to assembly of the adjustable inductance thereon.

Referring now to the drawing the mounting means 1 comprises a T-shaped resilient member of insulating material. An inductance coil 4 wound on a form 3 is held in the position shown in FIGURES 1 and 2. by an elongated ferrite core 5 which is axially movable within the form and extends through holes 6, 7 of the mounting means 1. The mounting means 1 is bowed to allow core '5 to pass therethrough, as best shown in FIGURE 2. The bowed mounting means 1, tends to straighten due to its resilience and, clamps the axial ends of the cores which secures it against inadvertent longitudinal movement within form 3. Holes 6, 7 are of such a size and are so spaced that the ends of coil form 3 project partially therethrough, as shown in FIGURE 2, therefore the coil form 3 is also clamped by the mounting means 1 so that the form 3 is also secured with respect to the core. Holes 6, 7 are too small to allow an end of coil form 3 to project completely therethrough. Holes 6 and 7 are preferably oxal shaped with the long axis coincident with the longitudinal axis of the cross bar strip of the T mount 1.

In order to adjust the inductance, the ends of the cross bar of the T of the mounting means 1 are forced toward each other or bowed further to release the core 5. The coil form 3 is still held between the bowed ends of the mounting means 1 however the core 5 may be adjusted readily with respect to form 3 to adjust the inductance to the required value. After release of the mounting means, the core 5 and form 3 are fixed in position relative to one another. Inherent in the invention is an adjustable inductor means comprising an elongated strip having a hole adjacent each end such as the cross bar of the T shaped mounting means I discussed above.

The mounting means 1 may be readily secured, by the leg or stem of the T, which provides a convenient foot for mounting an adjustable inductor to a metal chassis by means of a bracket 8 and one or two rivets or bolts. Generally the adjustment of the inductance will be performed after the mounting means 1 has been secured to a chassis and the inductance connected in its working circuit.

Modifications may be made which do not depart from the spirit and scope of this invention. For example the core may be secured to a chassis and the cross-bar portion only of the mounting means employed to clamp the coil in position on the core. Adjustment of the inductance is then accomplished by movement of the coil form with respect to the secured core.

What is claimed is: p

1. A clamping assembly for an adjustable inductor having an axially movable elongated core and coil means encircling said core; said assembly comprising a sheet of resilient insulating material having a pair of spaced apart openings therein for receiving said elongated core in a bowed position of said sheet and securing said core against longitudinal movement with respect to said sheet, said sheet enclosing said coil means within the bowed portion thereof between said openings, the space between said openings being selected for simultaneously contacting both axial ends of said coil means to secure it against longitudinal movement on said core.

2. A clamping assembly according to claim 1 wherein said sheet is T-shaped, said spaced holes being located in the cross-bar of said T and the stem of said T providing a mounting foot for said assembly.

3. A clamping assembly according to claim 1 wherein said holes are oval in shape and oriented in said sheet so that the longest axis of the oval substantially coincides with the longitudinal axis of said core.

4. An adjustable inductor means comprising, a resilient insulating member in the form of an elongated strip having a hole adjacent each end thereof, inductor coil means and an elongated ferrite core; said resilient member in a bowed position having said core passing through each of said holes for uniting said core and said member, said coil encircling the said core and being located between the ends of said member within the bow thereof, said member contacting the ends of said coil means for preventing longitudinal movement of the coil means with respect to the core.

5. An adjustable inductor means according to claim 4 with the addition of foot means integral with said strip.

6. An adjustable inductor means according to claim 4 8,273,097 3 4 wherein said holes are oval in shape and oriented in FOREIGN PATENTS said strip so that the longest axis of the oval substantially 1,357,115 2/1964 France. coincides with the longitudinal axis of said strip.

LEWIS H. MEYERS, Primary Examiner.

References Cited bythe Examine 5 ROBERT K. SCHAEFER, LARAMIE E. ASKIN,

UNITED STATES PATENTS Examiners.

1,631,2099 6/1927 Jewell 174161 X C. TORRES, Assistant Examiner. 

1. A CLAMPING ASSEMBLY FOR AN ADJUSTABLE INDUCTOR HAVING AN AXIALLY MOVABLE ELONGATED CORE AND COIL MEANS ENCIRCLING SAID CORE; SAID ASSEMBLY COMPRISING A SHEET OF RESILIENT INSULATING MATERIAL HAVING A PAIR OF SPACED APART OPENINGS THEREIN FOR RECEIVING SAID ELONGATED CORE IN A BOWED POSITION OF SAID SHEET AND SECURING SAID CORE AGAINST LONGITUDINAL MOVEMENT WITH RESPECT TO SAID SHEET, SAID SHEET ENCLOSING SAID COIL MEANS WITHIN THE BOWED PORTION THEREOF BETWEEN SAID OPENINGS, THE SPACE BETWEEN SAID OPENINGS BEING SELECTED FOR SIMULTANEOUSLY CONTACTING BOTH AXIAL ENDS OF SAID COIL MEANS TO SECURE IT AGAINST LONGITUDINAL MOVEMENT ON SAID CORE. 